Screen



Feb. 21, 1939. v

L. G. SYMO NS gunman Filed July so, 1937 5 Sheets-Sheet l W 6% m S WFeb. 21, 1939.

L. G. SYMQNS SCREEN 5 Sheets-Sheet 2 Filed July 30, 1957 .Zkflezezarlore)? d fy/ww 20 [tier/eggs.

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Feb. 21 1939. L, a SYMO'NS 1 2,148,139

SCREEN Fi led July 30, 1937 '5 Sheets-Sheet 3 L. G.- SYMONS Feb. 21,1939.

SCREEN Filed July 30, 1957 5 Sheets-Sheet 4 1 null: IN N NU Feb. 21,1939. c; sY oNs 2,148,139

SCREEN Filed July 30, 1957 5 Sheets-Sheet 5 .Zkmzzezfor H lire)?flyzzwas' U m Patented Feb. 21, 1939 scenes Loren G. Symons, Hollywood,Calif., assignor to N ordberg Manufacturing Company, Milwaukee, Wis, a.corporation of Wisconsin Application July 30, 1937, Serial No. 156,511

My invention relates to an improvement in screens and has for onepurpose the provision of a screen which shall be of lmaximum efficiencyand durability.

Another purpose is the provision. of a screen structure which shall be"relatively cheap and easy to manufacture.

Another purpose is the provision of improved means for imparting a snapaction surface or cloth whereby increased efliciency is obtained.

Another purpose is the provision of an improved screening means forsurface.

Figure 1 is a plan view with parts broken away;

Figure 2 is a. side elevation;

Figure 3 is a section on'the line 3--3 of Figure 2;

\ Figure 4 is a side elevation of the screen deck itself with parts insection;

Figure 5 is a partial transverse section through the screen deck onanenlarged scale.

Figure 6 is a section on the line-G-G of Figure 5;

Figure 7 is a side elevation of the actuating weight;

Figure 8 is a front elevation of 'the structure shown in Figure 7;

Figure 9 is a section on an enlarged scale along the line 9-9 of Figure7;

Figure 10 is a section on the line l0-|I| of Figure 9;

Figure 11 is a section on an enlarged scale on the line l|l I of Figure2; and

Figure 12 is a diagram of ment of the screen.

- Like parts are indicated by like symbols through the specification anddrawings.

Referring to the drawings, I indicates any suitable base or surface uponwhich the screen structure may be mounted. It will be understood thatthe two sides of the screen frame are substantial- 2 indicates a bottomstructural element .for one of the sides herein shown as an 3 indicatesa top side frame member. The members 2 and 3 are connected by verticalsupports 4 and 5, by an end inclined support 6, and an intermediateinclined support 6a. two side frames thus formed may;.be connected atthe top by any suitable transverse members members. 1 practical, it willbe understood that it is not ably identical.

angle.

I, and 9, herein shown as angle the vibratory move- 6 Claims. (01.209-329) and 8 may be connected for example by reinforcing andsupporting plates l0 and II. If desired any suitable motor support l2may be posi tioned 'adjustabiy upon the supporting plate I l and maycarry any suitable motor I3, with its drive pulley l4 and belt [5, thepurpose for which will later appear. Additional transverse members 2aand 212 may be provided to connect an; space the angle members 2.

I illustrate a screen box as including side plates l6, l6 which may bereinforced by strengthening plates i! to which the screening structureproper is secured; l8 indicates a transverse angle at the feed end ofthe screen box. A plurality of transverse plates 19 also connect theplates I! at various intervals along the length of the screen box.Intermediate these plates I!) are transverse plates 20. At the tops ofthe plates 19 are channels which may be welded thereto. In theintermediate plates I9 there are two such channels 2|, 2| securedtogether as by upper holding plates 22 which may also be welded thereto.In the end plates l9 at the opposite ends of the screen are merelysingle end channels 23 and at the tops of the intermediate plates 20 areupwardly extended channels 24. In the channels 2| and 23 are positionedstrips of material such as rubber indicated at 25 which may bereinforced with fabric or wire as a 26 and are provided with holes 21adapted to. receive the ends of flexible metal bars 28. It will beunderstood that each bar 28 at each end penetrates one of the strips 25,

In the particular form of the device herein shown, the bars are somewhatbowed upwardly since their intermediate portions rest upon rubber strips29 which are notched or apertured as at 30. As will be clear from Figure6, these apertures are so formed that the rubber more or less hugs theupper portion of each bar or rod 28 so that there is a grippingconnection between the strip 29 and the rods which lie in the notches30. It will be also observed, as in Figures 4 and 5, that the parts areso proportioned that the' to a screen free one or both ends from theapertures 27,

without straightening them, aswould be the case if for instance a highcarbon steel were used.

While this bowing of the rods is preferable and The rods are upwardlysomewhat bowed and the .remove them upwardly from the notches 30 andsoluteiy essential. In any event, the above described arrangement ofbars or rods and supporting and gripping rubber members and 29 providesan arrangement whereby the equivalent of screen mesh can be very simplyand cheaply applied to and withdrawn from the screen.

Also, a very resilient screening surface is provided and because of thekind of material employed it wears very slowly. A further advantage isthe fact that any area or section of excess wear can be replaced withoutthe necessity of replacing the portions of the screen surface which donot wear rapidly. For example, if the maximum zone of wear is at thefeed end of the screen, the bars 29 of the feed section may be replacedwithout the necessity of replacing the bars elsewhere in the screen. Thebars may be turned end for end to advantage.

Outer plates are secured, for example by welding, to the outer faces ofthe side plates I0. As will be clear from Figure 4, these outer platesextend upwardly above the top of the screen box as at 35. Between theseupward projecting por-,

tions 36 is a hollow spacing bar or cylinder 31 which may be held at itsends in flanged rings 38. Alined with the spacer 31 is an outer stub 39flanged as at 40. The flanged stubs the flanged rings 39 are securedtogether and to the members I6 and 35 by any suitable means as forexample by the bolts 4I. Surrounding the stubs 39 are rubber bushings 42which may be reinforced with fabric as at 43. 39a is any suitableretaining flange for preventing axial displacement. 45 is a screenactuating arm having an eye 45 surrounding the bushing 42. It is hereinshown as split, the two parts of the eye being secured together by thebolts 41.

At each end of each side of the screen box and secured to the members I0are angles 50, 5| arranged back to back. Held between them is a plate 52with an outward extension 53 to which are secured leaf springs 54 whichproject upwardly and in turn are secured at their upper ends toextensions 55 extending inwardly from the inclined supports 9 and 5a ofthe structural members 2; 3. Thus each end of the screen box is securedby a pair of inclined depending leaf spring structures.

Extending across the feed end of the screen box is an angle 55 which iswelded to the brackets I 53 and to reinforcing angles 51. It isapertured at each end as at 59 to permit the passage therethrough ofpins 59 which have at their outer ends abutments 50. An angle 9| extendsinwardly from each of the screen frames and are welded to the diagonalsupports, 611. They are also apertured to permit the passagetherethrough of the pin 59. Compressed at each end between the angle BIand the abutment 60 is a spring 62. The

function of these springs is to hold the screen' box normally in theposition shown with the leaf springs 54 at right angles. In case thereis a necessity for adjustment, the pin 59 is provided of the screen boxproper.

rests on a bracket 16 secured to the frame members 2 with its centeringmember II. There is one of these springs at each side of the screen andthus each of the weights I2 is supported on or floated on one of thesprings 15 from the main frame.

I9, I0 are bearing members intermediate each pair of side plates, thesemembers being shown also in Figure 11 as surrounded by rubber bushings19 which in turn are surrounded by the split eye of the arm 45. Thus thearm 45 serves as a vibrating connection between the screen box structureand the weight structure.

The pairs of side arms I0, I0 and II, II are connected as by transversechannels 8|, 82 which define a species of box or housing which is roofedby a' plate 83, the central part of which is upwardly extended or bowedas at 84. 85 indicates spring Penetrating abutments secured to thechannels 8| at each end and which penetrate the springs 86 which in turnrest on brackets 81 secured to the vertical supports 5 of the sideframes. Thus the springs 88 float and support the upper portion of theabove described weight structure. v

The means for vibrating the weight structure and screen includes ahollow shaft 90 which is connected by a flexible driving connection 9|the details of which do not form part of the present invention with ashaft 92 journaled in a bearing 93 supported on one of the structuralmembers 3 along the upper edge of the main frame. It carries a drivenpulley 94 about which pass the belts I5. 95 is another flexibleconnection whereby the shaft 90 rotates a counterweight structure. Thecounterweight structure is mounted in a pair of bearings including fixedouter sleeves 96, a roller or ball race structure 91, and the shaftportions 98 rotating therewithin. Intermediate these shaft portions 98is an unbalanced mass of metal 99, which includes circular plates I00provided with a plurality of apertures IN. The plates are held to themass 99 as by the bolts I02. I 03 is an adjustable mass or counterweightwhich may be bolted to the plates I00 at any desired position as by thebolts I04. It will be understood that either by changing therelationship between the member I03 and the plates I00 or by changingthe position of the plates I00 in relation to the mass 99, the unbalanceof the rotor may be widely varied, as when it is desired to change thestroke or amplitude of vibration.

Note that the bearing members 96 are secured to the transverse channels8| and -82 by bolts I05.

It will be understood that whereas I have herewith shown and described apractical operative device, nevertheless many changes might be made inthe size, shape, number and disposition of parts without departing fromthe spirit of the invention and I wish, therefore, that my showing betaken as in a sense diagrammatic.

It will be understood, for example, that whereas I have described andshown an element including the arms 10, II, which I have describedgenerally as a weight, I do not wish to be limited to the use ofspecific weight members I2. I consider it important, however, that somestructure having substantial weight shall be movably mounted on theframe or its equivalent and shall serve as the means for controlling thevibration Clearly vasingle weight or a plurality of weights could beused, and a wide variety of structural connections therefor.

The use and operation of my invention are as follows:

I provide an economical and eificient screen in which the direction ofmovement of the screen itself is linear.

porting springs 54. While the movement is ar.- cuate, the radius of thearc is so great that the effect is so simple linear movement and thescreen is simply vibrated in a plane which is at right angles to theextension of the supporting springs. There is no end thrust against thesprings themselves and the only' movement imparted to-the screen is thevibration in the said very slightly arcuate path.

In order to impart this movement to the screen, I have employed theabove described intermediate weight structure which is floated on thesprings 15 and 86, and which includes-heavy weights. The weightstructure as a wholeis vibrated by rotation of the unbalanced member orrotor including the members 99 and I03 which may be adjusted in relationto each other in order to get any desired stroke within a very substantial range. Thus when the motor I3 is running it imparts a rapidrate of rotation to the unbalanced rotor and the result is a verysubstantial vibration of the weight structure.

The weight structure, being spring floated on the main frame, transmitsa minimum 'of vibration to the main frame and the supporting surfaces orbuilding. The vibration of the weight structure in turn is imparted tothe screen box,

proper through the arms or conrods 45. As each end of each arm 45 hasassociated therewith a rubber bushing 42 or I9, in practice this use ofrubber bushings causes a snap action or a sudden change in direction ofmovement of the screen which imparts a very efficient screening eifect.Furthermore, the torsion of the rubber bushings permits the screen boxitself to be driven with a minimum endwise thrust on the supportingsprings 54, which would otherwise result because of the slightly arcuatepath of movement of the deck.- Whether the path of vibration of theweight structure is slightly oval or somewhat squared or approximatelycircular, the vibration of the screen box proper will be linear.

In analyzing the movement and mode of operation of the present screen,the flexible leaf mounting of the deck on the leaves" 54, without anybushings or bearings, has in practice proved highly satisfactory. Theseleaves are preferably ilght spring leaves, which makes for longer lifethe ideal vibrator has a minimum number of As shown for example inFigure 9, my unbalanced rotor, including the portions 99 and bearings.

I93, rotates in'only two bearings. In order to provide a shaft betweenthe bearings of maximum strength and simplicity I place the bearingsclose together as shown in Figure 9. The out of balance shaft, includingthe members 98 and-99,

is preferably cast in one piece, which makes it extremely rigid.

I have provided what in practice has turned out to be a highly eflicientconnection between the 4 unbalanced weight structure 99 and the deckwhich is capable of transmitting linear motion to That is to say, itacts as if it were rotated about the upper ends of the sup the deckwhile allowing substantially free motion to the vibrator structure. Ihave therefore employed the arms or conrods 45 provided at each end withrubber bushings or torsion members 42 the deck, it will be well toconsider the diagram of Figure 12. The weight W of which X is the centerof gravity, may be considered as an inertia member resisting themovement of the vibrator or unbalancedmember 99 only in the discretionof the line A--B. In this direction the vibrator would have to movevitself and the weight; In the direction C-D the vibrator has to moveitself plus the weight of the deck, but exerts a leverage on the deckmathematically as the distance ZX is to the distance YX. If the distanceXY were the same as the distance YZ the force of the vibrator to movethe deck would have to equal only one half of the resistance of thedeck, as the leverage would be 2 to 1.- This in turn would mean that inorder to make the resistance to the vibrator in the direction AB thesame as C--D, the weight W would necessarily be less than the weight ofthe deck.

Thus placing the vibrator above the point Y where the conrod 45 isconnected to the weight structure does two things. In the first place,it places the vibrator at a level higher than the screen or deck itself,where it does not interfere with the movement of the deck or with thefeed of bulky material over the deck. In the second place, it enables areduction of the weight W, which has no function except to act as acontrolling medium. The entire weight and cost of the screen may bereduced without any sacrifice of efficiency.

In referring to Figure 12, the motion of the deck is indicated by thearrow M, it being practically linear and only very slightly arcuate,being in effect an arc with its center at the upper edge of the deck, thradius defined by the springs 54. The motion of t e weight is almostlinear and at about ninety degrees angle to the motion of the deck. Theactual motion is indicated for example by the flat or elongated ellipseshown at E. The vibration of the vibrator or the unbalanced rotor may begenerally circular, which effects a substantial reduction of the load onthe bearings, as compared for example to the bearing load caused by ovalvibration. The parts may be so proportioned as to cause the shaft Z ofFigure 12 to vibrate in a. practically circular path or vibration form.In effect what I do in applying a linear vibration to the screen deck isto employ a means for controlling the rotation of the unbalanced weight99 by subjecting itto resistance at about ninety degrees to the axis ofresistance or axis of pull between the vibrator unit as a .whole and thescreen deck.

The vibrator and the Weight are floated on the base in such a mannerthat no vibration can be transmitted to the base except the very smallamount that might be caused by the lengthening and shortening of thesprings 15 and 88 shown in Figure 2. In actual operation of machines,the

lack of vibration is marked, a fact which permits the employment of acomparatively light base. This use of a. light base makes'for a moreeconomical machine. Also, the fact that the weight 'does not have to beas heavy as the deck makes the entire screen economical to build.

In connection'with the operation of the screen above described, therubber bushings 42 and I! 75 4 its movement before the deck does.

In practice, as tested in the actual use of screens made in accordancewith the above description, the result is a snappy or quick reversal ofaction at the ends of the strokes and an increase in screeningefficiency. This snap action is obtained without acceleration of thespeed unit itself and in fact is more effective at certain lower speedsthan at higher speeds.

With the snap action obtained by speeding up the power plant or thetransmission, the material is in practice thrown sufllciently high inthe air at each impulse so that it does not return to the surface of thedeck and come to rest before the succeeding impulse. This isdisadvantageous because the screening mesh meets the material at themaximum upward and forward speed of the mesh and imparts a battingaction. Where the rate of vibration can be made somewhat slower, thematerial has time during impulses to settle back to the cloth. Theresult is a better screening action and less damage to the cloth, with aresultant increase in the capacity of the screen.

In connection with particles of critical size, if they are allowed tosettle upon the surface oi! the deck, they can slip through the deckapertures. But they can easily be batted upwardly away from the deck ifthey are struck by the screen cloth when the cloth or deck is in rapidmotion. The advantage of the slower movement when accompanied by thesnap action obtained by the rubber bushings may be illustrated bychanging the speed of movement or vibration rate of a screen made ingeneral accordance with the present description and drawings. In aparticular screen, tests showed that the screen had a larger capacity,and that individual particles actually moved faster, and that the screencleaned cleaner, when run at 900 R. P. M. than when run at 1250 R. P. M.This was because the lower rate of speed prevented the batting action.The lower rate, in turn. was permitted because of the snap action of therubber bushings I claim: I

'1. In a screen, a base, a screen deck yieldingly mounted on said base,a vibrating unit yieldingly mounted on said base independently of saiddeck, and including an unbalanced rotary member and means for rotatingit and for thereby vibrating said unit, a weight on said unit remotefrom said rotary member, a structural member connecting said weight andsaid rotary member, and an actuating connection between said deck andsaid structural member, connected to said structural member intermediatesaid unbalanced rotary member and the center of gravity of said weight.

2. In a screen, a base, a screen deck yieldingly mounted on said base, avibrating unit yieldingly mounted on said base independently of saiddeck, and including a transverse member extending across the screenabove the screen deck and having side arms depending from each endthereof, weights on the lower portions of said side arms, an unbalancedrotary member mounted upon said transverse member, and means forrotating it and for thereby vibrating said unit, and actuatingconnections between said deck and said side arms, connected to said sidearms intermediate said weights and said unbalanced rotary member.

3. In a screen, a base, a screen deck yieldingly mounted on said base, avibrating unit yieldingly and independently mounted on said base, andincluding an unbalanced rotary member and means for rotating it and forthereby vibrating said unit, a weight on said unit remote from saidrotary member, a structural member connecting said weight and saidrotary member, and an actuating connection between said deck and saidstructural member, intermediate said unbalanced rotary member and thecenter of gravity of said weight.

4. In a screen, a base, a screen deck yieldingly mounted on said base, avibrating unit yieldingly and independently mounted on said base, andincluding an unbalanced rotary member and means for rotating it and forthereby vibrating said unit, a weight on said unit remote from saidrotary member, a structural member connecting said weight and saidrotary member, and an actuating connection between said deck and saidstructural member, intermediate said unbalanced rotary member and thecenter of gravity of said weight, said actuating connection including aconnecting rod generally perpendicular to a line connecting the centerof rotation of said unbalanced rotary member and the center of mass ofsaid weight.

5. In a screen, a base, a screen deck yieldingly mounted on said base, avibrating unit yieldinglyand independently mounted on said base, andincluding an unbalanced rotary member and means for rotating it and forthereby vibrating said unit, a weight on said unit remote from saidrotary member, a structural member connecting said weight and saidrotary member, and an actuating connection between said deck and saidstructural member, intermediate said unbalanced rotary member and thecenter of gravity of said weight, said actuating connection including aconnecting rod generally perpendicular to a line connecting the centerof rotation of said unbal- 'anced rotary member and the center of massof the horizontal.

6. In a screen, a base. a screen deck yieldingly mounted on said base,and means for constraining it to a generally linear vibration in a pathinclined substantially from the horizontal, a vibrating unit yieldinglyand independently mounted on said base and including an unbalancedrotary member and means for rotating it and for thereby vibrating saidunit, a weight on said unit remote from said rotary member, a structuralmember connecting said weight and said rotary member, and an actuatingconnection between said deck and said structural member, intermediatesaid unbalanced rotary member and the center of gravity of said weight,including a connecting rod generally parallel with the path

